1. Field of the Invention
This invention relates to a novel process for industrially preparing 21-desoxyprednisolone 17-esters.
2. Description of the Background Art
21-Desoxyprednisolone 17-esters are compounds having a chemical structure of formula (IV), ##STR2## wherein R.sub.1 is a lower alkyl or aralkyl group. They are useful pharmaceutical compounds possessing an excellent local anti-inflammatory action (Japanese Patent Publication No. 20697-1971).
A number of processes are known for producing these compounds. All known processes, however, have drawbacks such as a low production yield, requirement of complicated purification procedures for eliminating 21-esters which are by-produced in these processes, and the like. None of them are suitable as a process for the industrial production of these compounds.
In view of this situation, the present inventors have undertaken extensive studies and have developed a novel process which is free from these drawbacks and can be applicable to industrial production of 21-desoxylorednisolone 17-esters.